SANTA CLARA, Calif. — After blowing a fourth-quarter lead against a heated division rival Sunday afternoon, the San Francisco 49ers were left with an all-too-familiar emotion.

This time, the Seattle Seahawks stormed down the field to score the game-winning touchdown with 12 seconds left, turning a certain loss into a 20-17 victory.

Given the feeling in the Niners’ collective stomach, it might as well have been their Week 3 loss to the Los Angeles Rams or their Week 5 upset against the Arizona Cardinals.

“It’s annoying, honestly,” the linebacker Fred Warner said. “It’s not like us. But that’s what we’ve shown this year, so I think until we stop doing that, then that’s who we are.”

What the 49ers are now is a 5-5 team teetering on the brink of a losing season. That loss dropped them to 1-3 in NFC West games and saw a defensive end Nick Bosa is nursing a hip and oblique injury that kept him out for most of Sunday’s second half and could linger for weeks to come.

All of which would make the Niners’ path to a third straight division crown, or any playoff berth, substantially more difficult.

The frustration Warner shares with his teammates isn’t just the record against division foes, but how San Francisco achieved it. According to the Elias Sports Bureau, the 49ers have three losses in the division when leading in the final two minutes of regulation, which is tied for the most such losses by a team in a season since the 1970 merger.

San Francisco’s three losses have come in just four chances and are tied with the 2001 Carolina Panthers, 2000 Los Angeles Chargers, 1996 Baltimore Ravens and 1994 Washington Commanders as the only teams to have that many losses in those situations . resume.

Losing a third game while leading in the fourth quarter tied the Niners for the most such leads blown by any team this season, joining the Jacksonville Jaguars and Cincinnati Bengals. It all led coach Kyle Shanahan to strike a message similar to the one he’s embraced after several losses this season (and even a few wins).

“We had every opportunity to run with it and we put it away,” Shanahan said. “(We) missed some opportunities to do that and … let people sit, that’s what happens.”

Indeed, the 49ers had multiple chances to build a large, perhaps insurmountable lead against the Seahawks. But a series of self-inflicted mistakes prevented that from happening.

Played without a tight end George Kittle Due to a hamstring injury, the Niners were sluggish on offense, finishing with just 277 yards of offense, their fewest production in a game since Week 6 of the 2023 season. The longest play of the day was just 22 yards , tied for the second-fewest in a game since Shanahan took over in 2017 (19 yards was the longest play in a 2020 loss to Washington).

More maddening for the Niners, however, was their inability to avoid penalties that wiped out multiple scoring chances. San Francisco racked up nine penalties for 54 yards, with seven of those penalties coming against the offense. In recent seasons, the Niners have had no trouble overcoming such mistakes, but this team hasn’t proven capable of the same kind of resilience in the game.

“Obviously (in) past years, it’s like we put that behind us and play the next play,” quarterback Brock Purdy said. “Just because we’ve been successful the last few years doesn’t mean that just because something bad happens to us, we’re going to magically make up for it. We have to have the chip on our shoulder to go get it each. Play, down and play We just have to get back to that mentality.”

With seven games left in the season for the 49ers to rediscover what has made them successful in recent years, the clock is undoubtedly ticking for a tough two-game stretch that includes trips to Green Bay and Buffalo. That they might have to do it without Bosa I just understand to make those tasks harder.

Bosa has been dealing with a right hip pointer and an oblique problem all week that he said would be “close” if he even plays against the Seahawks. Bosa started the game and had four tackles and 1.5 sacks before leaving early in the second half.

Bosa injured his other hip and oblique when he brought in the Seahawks quarterback Geno Smith down for a sack with 9:26 left in the third quarter. He stayed on the field for one more play before checking out and never returned. After the game, Bosa said he felt he was “compensating” for his previously injured hip and oblique and lamented missing Seattle’s game-winning drive.

The Seahawks averaged just 3.3 yards per play when Bosa was on the field, compared to 6.1 yards when he was off Sunday. Seattle also scored all 20 of its points with Bosa out.

“Brutal,” said Bosa. “The most important moment of the game for me to be there, I couldn’t be. I hate the time lost. That’s why I went last week. I hope it’s not too long (to be out).”